Filtration media pack, filter elements, and air filtration media

ABSTRACT

A filtration media pack including a plurality of layers of filter media is disclosed. The media pack includes fluted sheets and a facing sheet, with a plurality of flutes extending between the fluted sheets and the facing sheets. In an embodiment, the fluted sheet includes a plurality of protrusions that contact the facing sheet.

This application is a continuation of U.S. application Ser. No.15/476,405, filed Mar. 31, 2017, which is a continuation of U.S.application Ser. No. 14/591,731, filed Jan. 7, 2015, now U.S. Pat. No.9,623,362, which issued on Apr. 18, 2017, claiming priority to U.S.Provisional Application No. 62/077,891, filed Nov. 10, 2014 and U.S.Provisional Application No. 61/924,696, filed Jan. 7, 2014; the entirecontents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to filtration media packs that can be usedto form filter elements. The invention additionally relates to filterelements and filtration media.

BACKGROUND OF THE INVENTION

Fluid streams, such as air streams, often carry contaminant material. Inmany instances it is desired to filter some or all of the contaminantmaterials from the fluid streams. For example, particulate contaminantscan be carried by air streams into internal combustion engines formotorized vehicles or for power generation equipment. It is preferredfor such systems that selected contaminant material, such as particulatecontaminants, be removed from (or have its level reduced in) the airstream.

A variety of fluid filter arrangements have been developed forcontaminant reduction. In general, however, continued improvements aresought.

SUMMARY OF THE INVENTION

The present disclosure is directed to a filtration media pack containinga plurality of layers of media, including fluted sheets and facingsheets, as well as filter media packs, filter elements and filter media.In certain embodiments a plurality of flutes extend between the flutedsheets and the facing sheets, with a first portion of the plurality offlutes closed to unfiltered air flowing into the first portion of theplurality of flutes, and a second portion of the plurality of flutesclosed to unfiltered air flowing out of the second portion of theplurality of flutes. Air passing into one face of the media pack and outthe other face passes through media to provide filtration of the air. Inspecific embodiments the fluted sheet comprises a plurality ofprotrusions, at least a portion of the protrusions contacting the facingsheet. In other specific embodiments the facing sheet comprises aplurality of protrusions, at least a portion of the protrusionscontacting the fluted sheet. It will be understood that in someimplementations other portions of the flutes are plugged, such thatclosing of the flutes can occur at either end of the flutes or atinterior locations of the flutes (such as half way from the ends of theflutes).

The filtration media pack can include protrusions having, for example, aheight of from 0.2 to 3 millimeters. In some embodiments the protrusionshave a height from 0.4 to 24 times the thickness of the media formingthe fluted sheet. In an embodiment the protrusions have a height of lessthan 3 times the thickness of the media forming the fluted sheet. Incertain implementations the protrusions have a height of at least 2times the thickness of the media forming the fluted sheet. Optionallythe protrusions are from 10 to 90 percent of the height of the flutes inthe fluted sheet. Thus, the height of the protrusions can add, forexample from 10 to 90 percent to the height of the flutes excluding theprotrusions. In some embodiments the protrusions are less than 30percent of the height of the flutes in the fluted sheet. The protrusionsmay be, for example, at least 15 percent of the height of the flutes inthe fluted sheet. The protrusions are from 1 to 20 percent of the widthof the flutes in the fluted sheet in example implementations. Inspecific embodiments the protrusions are less than 10 percent of thewidth of the flutes in the fluted sheet. The protrusions can be, forexample, at least 5 percent of the width of the flutes in the flutedsheet.

The protrusions between a first face of the filtration media pack and asecond face of the filtration media pack can be of equal height in someembodiments, but vary in height in other embodiments. The protrusionsbetween the first face of the filtration media pack and the second faceof the filtration media pack can be tapered in height with respect toeach other.

The filtration media pack can be used to filter a fluid that is agaseous or liquid substance. An exemplary gaseous substance that can befiltered using the filtration media is air, and exemplary liquidsubstances that can be filtered using the filtration media includewater, oil, fuel, and hydraulic fluid. The filtration media pack can beused to separate or remove at least a portion of a component from afluid to be filtered. The component can be a contaminant or anothermaterial targeted for removal or separation. Exemplary contaminants andmaterials targeted for removal include those characterized as solids,liquids, gases, or combinations thereof. The contaminants or materialstargeted for removal can include particulates, non-particulates, or amixture thereof. Materials targeted for removal can include chemicalspecies that can be captured by the media. In certain implementationsthe media surface can remove contaminants without passing fluids(liquids or gases) through the media, in which case the flutes can beopen along their length, rather than closed. The reference to removal ofcomponents and contaminants should be understood to refer to thecomplete removal or separation or a partial removal or separation.

The protrusions can be formed, for example, by a roller or other devicehaving raised areas and depressions corresponding to the flutes andprotrusions.

This summary is an overview of some of the teachings of the presentapplication and is not intended to be an exclusive or exhaustivetreatment of the present subject matter. Further details are found inthe detailed description and appended claims. Other aspects will beapparent to persons skilled in the art upon reading and understandingthe following detailed description and viewing the drawings that form apart thereof, each of which is not to be taken in a limiting sense. Thescope of the present invention is defined by the appended claims andtheir legal equivalents.

BRIEF DESCRIPTION OF THE FIGURES

The invention may be more completely understood in connection with thefollowing drawings, in which:

FIG. 1 is a perspective view of a sheet of fluted filter media,constructed and arranged according to an embodiment of the invention.

FIG. 2 is a perspective view of a sheet of fluted filter media and asheet of facer media, constructed and arranged according to anembodiment of the invention.

FIG. 3 is a front view of a sheet of fluted filter media and a sheet offacer media, constructed and arranged according to an embodiment of theinvention.

FIG. 4 is a front view of a plurality of sheets of fluted and facermedia, constructed and arranged according to an embodiment of theinvention.

FIG. 5 is a front view of a sheet of fluted filter media and a sheet offacer media, constructed and arranged according to an embodiment of theinvention.

FIG. 6 is a front view of a plurality of sheets of fluted and facermedia, constructed and arranged according to an embodiment of theinvention.

FIG. 7 is an enlarged front view of a sheet of fluted media and facermedia constructed and arranged according to an embodiment of theinvention, showing dimensions of example flutes.

FIG. 8 is an enlarged perspective view of a sheet of fluted media andfacer media constructed and arranged according to an embodiment of theinvention, showing dimensions of example protrusions on the flutes.

FIG. 9 is a perspective view of a sheet of fluted filter media,constructed and arranged according to an embodiment of the invention,showing variable spacing of protrusions on the fluted filter media.

FIG. 10 is a front view of a sheet of fluted filter media and a sheet offacer media, constructed and arranged according to an embodiment of theinvention shown in FIG. 9.

FIG. 11 is a perspective view of a sheet of fluted filter media,constructed and arranged according to an embodiment of the invention.

FIG. 12 is a front view of a sheet of fluted filter media and a sheet offacer media, constructed and arranged according to an embodiment of theinvention shown in FIG. 11.

FIG. 13 is a perspective view of a sheet of fluted filter media,constructed and arranged according to an embodiment of the invention,showing single protrusions on the fluted media sheet.

FIG. 14 is a front view of a sheet of fluted filter media and a sheet offacer media, constructed and arranged according to an embodiment of theinvention shown in FIG. 13.

FIG. 15 is a perspective view of a sheet of fluted filter media,constructed and arranged according to an embodiment of the invention.

FIG. 16 is a front view of a sheet of fluted filter media and a sheet offacer media, constructed and arranged according to an embodiment of theinvention shown in FIG. 15.

FIG. 17 is a perspective view of a sheet of fluted filter media and asheet of facer media, constructed and arranged according to anembodiment of the invention.

FIG. 18 is a perspective view of a filter element constructed andarranged according to an embodiment of the invention.

FIG. 19 is a graphical representation of channel area and protrusionheight ratios of a filter media constructed and arranged in accordancewith a first example embodiment of the invention.

FIG. 20 is a graphical representation of corrugated and flat sheetlengths of a filter media constructed and arranged in accordance with afirst example embodiment of the invention.

FIG. 21 is a graphical representation of upstream and downstreamprotrusion heights of a filter media constructed and arranged inaccordance with a first example embodiment of the invention.

FIG. 22 is a graphical representation of channel area and protrusionheight ratios of a filter media constructed and arranged in accordancewith a second example embodiment of the invention.

FIG. 23 is a graphical representation of corrugated and flat sheetlengths of a filter media constructed and arranged in accordance with asecond example embodiment of the invention.

FIG. 24 is a graphical representation of upstream and downstreamprotrusion heights of a filter media constructed and arranged inaccordance with a second example embodiment of the invention.

FIG. 25 is a graphical representation of channel area and protrusionheight ratios of a filter media constructed and arranged in accordancewith a third example embodiment of the invention.

FIG. 26 is a graphical representation of corrugated and flat sheetlengths of a filter media constructed and arranged in accordance with athird example embodiment of the invention.

FIG. 27 is a graphical representation of channel area and protrusionheight ratios of a filter media constructed and arranged in accordancewith a fourth example embodiment of the invention.

FIG. 28 is a graphical representation of corrugated and flat sheetlengths of a filter media constructed and arranged in accordance with afourth example embodiment of the invention.

FIG. 29 is a graphical representation of upstream and downstreamprotrusion heights of a filter media constructed and arranged inaccordance with a fourth example embodiment of the invention.

FIG. 30 is a graphical representation of channel area and protrusionheight ratios of a filter media constructed and arranged in accordancewith a fifth example embodiment of the invention.

FIG. 31 is a graphical representation of corrugated and flat sheetlengths of a filter media constructed and arranged in accordance with afifth example embodiment of the invention.

FIG. 32 is a graphical representation of upstream and downstreamprotrusion heights of a filter media constructed and arranged inaccordance with a fifth example embodiment of the invention.

While the invention is susceptible to various modifications andalternative forms, specifics thereof have been shown by way of exampleand drawings, and will be described in detail. It should be understood,however, that the invention is not limited to the particular embodimentsdescribed. On the contrary, the intention is to cover modifications,equivalents, and alternatives falling within the spirit and scope of theinvention.

DETAILED DESCRIPTION OF THE INVENTION

The present disclosure is directed to fluid filtration media packs, suchas gas or liquid filtration media packs containing a plurality of layersof media, including fluted sheets and facing sheets. The filteredgaseous fluid can be, for example, air. A plurality of flutes extendbetween the fluted sheets and the facing sheets. In certainimplementations a first portion of the plurality of flutes is closed tounfiltered air flowing into the first portion of the plurality offlutes, and a second portion of the plurality of flutes is closed tounfiltered air flowing out of the second portion of the plurality offlutes. Air passing into the media pack and out the other face passesthrough media to provide filtration of the air. In specific embodimentsthe fluted sheet comprises a plurality of protrusions, at least aportion of the protrusions contacting the facing sheet. In otherspecific embodiments the facing sheet comprises a plurality ofprotrusions, at least a portion of the protrusions contacting the flutedsheet.

In certain embodiments the repeating pattern of flutes comprises atleast one ridge extending along at least a portion of the flute lengthbetween adjacent peaks. The ridge can comprise a discontinuity in thecurvature of the flute between the adjacent peaks. The flutes often alsocontain a central peak. Often the protrusions are positioned on eitherside of this peak. In some embodiments the protrusions are located onthe peak itself. In either configuration the protrusions are configuredto reduce masking between the fluted sheet and facing sheet. Masking canrefer to areas of filter material that have restricted or reduced fluidflow, such as due to a blockage or contact. Masking refers to areaswhere two sheets of filter material can contact each other and reducefluid flow through the sheets of filtration media thereby decreasing theamount of usable filter material.

The protrusions are generally small protrusions or other extensionsextending upward from the surface of the media. In typical embodimentslarge numbers of protrusions will be present on the fluted media. Theprotrusions, when viewed from above the media surface can be, forexample, round, oval, elliptical, or polygonal. Typically theprotrusions will have curved edges so as to minimize media strain. Theprotrusions can vary in size and shape, and upstream surfaces of themedia will often have different shapes, sizes, and/or numbers ofprotrusions than the downstream surfaces. Indeed, it is possible to haveprotrusions on just one side of the media, either on the upstream sideor the downstream side.

Thus, in some implementations the flutes contain peaks, wherein thepeaks do not substantially contact the facing sheet along the entirelength of the flutes because the flutes are held off the facing sheetsby the protrusions. In certain aspects the filtration media packincludes a plurality of layers of single face media comprising a flutedsheet, a facing sheet, and a plurality of flutes extending between thefluted sheet and the facing sheet. A first portion of the plurality offlutes is closed to unfiltered air flowing into the first portion of theplurality of flutes, and a second portion of the plurality of flutes isclosed to unfiltered air flowing out of the second portion of theplurality of flutes, such that air passing into one of the first face orthe second face of the media pack and out the other of the first face orthe second face of the media pack passes through media to providefiltration of the fluid (such as air). At least one of the flutescomprises at least one contact region, the contact region comprising atleast one island extending from at least one of the facing sheet andfluted sheet.

In certain implementations the filtration media pack comprises aplurality of layers of single face media wherein the layers of singleface media comprise a fluted sheet, a facing sheet, and a plurality offlutes extending between the fluted sheet and the facing sheet andhaving a flute length extending from a first face of the filtrationmedia pack to a second face of the filtration media pack. A firstportion of the plurality of flutes is closed to unfiltered air flowinginto the first portion of the plurality of flutes, and a second portionof the plurality of flutes is closed to unfiltered air flowing out ofthe second portion of the plurality of flutes, so that air passing intoone of the first face or the second face of the media pack and out theother of the first face of the second face of the media pack passesthrough media to provide filtration of the air. The fluted sheetincludes, in such implementations, repeating internal peaks facingtoward the facing sheet and repeating external peaks facing away fromthe facing sheet. A repeating pattern of flutes comprise at least oneridge extending along at least a portion of the flute length betweenadjacent peaks. A plurality of island protrusions extend from the fluteand contacting the facing sheet, wherein at least one of the pluralityof protrusions is located between a ridge and a peak of the flute. Theisland protrusions extend above a region of media substantially free ofprotrusions.

In some implementations the filtration media pack has a plurality oflayers of single face media comprising a fluted sheet, a facing sheet,and a plurality of flutes extending between the fluted sheet and thefacing sheet. A first portion of the plurality of flutes is closed tounfiltered air flowing into the first portion of the plurality offlutes, and a second portion of the plurality of flutes is closed tounfiltered air flowing out of the second portion of the plurality offlutes, such that air passing into one of the first face or the secondface of the media pack and out the other of the first face or the secondface of the media pack passes through media to provide filtration of theair. The fluted sheet further comprises a plurality of protrusions, theprotrusions being non-uniformly distributed along the fluted sheet.

The filtration media pack can comprise a plurality of layers of singleface media comprising a fluted sheet, a facing sheet, and a plurality offlutes extending between the fluted sheet and the facing sheet. A firstportion of the plurality of flutes is closed to unfiltered air flowinginto the first portion of the plurality of flutes, and a second portionof the plurality of flutes being closed to unfiltered air flowing out ofthe second portion of the plurality of flutes, such that air passinginto one of the first face or the second face of the media pack and outthe other of the first face or the second face of the media pack passesthrough media to provide filtration of the air. The fluted sheet alsoincludes a plurality of protrusions, the protrusions making contact withthe facing sheet. The protrusions are substantially absent from theportions of the fluted sheet not in contact with the facing sheet.

In some embodiments the filtration media pack comprises a plurality oflayers of single face media comprising a fluted sheet, a facing sheet,and a plurality of flutes extending between the fluted sheet and thefacing sheet. A first portion of the plurality of flutes is closed tounfiltered air flowing into the first portion of the plurality offlutes, and a second portion of the plurality of flutes is closed tounfiltered air flowing out of the second portion of the plurality offlutes, such that air passing into one of the first face or the secondface of the media pack and out the other of the first face or the secondface of the media pack passes through media to provide filtration of theair. The fluted sheet comprises a plurality of protrusions, theprotrusions covering only a portion of the fluted sheet.

The filtration media pack can include a plurality of layers of singleface media comprising a fluted sheet, a facing sheet, and a plurality offlutes extending between the fluted sheet and the facing sheet. A firstportion of the plurality of flutes is closed to unfiltered air flowinginto the first portion of the plurality of flutes, and a second portionof the plurality of flutes being closed to unfiltered air flowing out ofthe second portion of the plurality of flutes, such that air passinginto one of the first face or the second face of the media pack and outthe other of the first face or the second face of the media pack passesthrough media to provide filtration of the air. The fluted sheetcomprises a plurality of protrusions extending from a remainder of thefluted sheet, the protrusions having a non-constant cross-section on thefluted sheet in all axes.

In reference now to the figures, FIG. 1 shows a perspective view of afluted sheet 100 of filter media. The fluted sheet 100 can include afirst edge 102 and a second edge 104. The fluted sheet 100 can includeone or more flutes 106, such as a channel or a peak and a valley. Theflutes 106 can extend from the first edge 102 to the second edge 104.The fluted sheet 100 can include first flutes 106 on one side of thefluted sheet 100 and second flutes 108 on the opposite side of thefluted sheet 100. The flutes 106, 108 can be asymmetric, such as whenthe first flutes 106 have a different shape or cross sectional area thanthe second flutes 108.

When formed into a media pack or filter element, the first flutes 106can be closed to unfiltered air flowing into the second flute 108, suchthat air in the second flute 108 has been filtered. The flutes can betapered, such as having a larger opening on one of the ends compared tothe other end. In the embodiment of FIG. 1, the flutes are tapered, suchthat the first flute 106 is larger than the second flute 108 at thefirst edge 102, and the second flute 108 is larger than first flute 106at the second edge 104. In some embodiments the media includes taperedand non-tapered portions. For example, a first portion of the media canbe tapered, with a second portion not being tapered. In an exampleembodiment upstream portion of the media is substantially non-taperedfor the majority of the length of the flute, with tapering of thedownstream portion only. In some embodiments at least half of theupstream length of the flutes is not tapered, while in other embodimentsat least three quarters of the upstream length of the flutes is nottapered.

The fluted sheet 100 can include repeating peaks 112, 114 and aplurality of protrusions 116. The protrusions 116 can be disposed on apeak 112, 114, or adjacent to a peak, such as just offset from the tipof the peak. The protrusions 116 can be discontinuous, such that thereare portions along the flutes 106 between the first edge 102 and thesecond edge 104 that do not include a protrusion. The protrusions 116can be arced, such as having a non-planar top surface. The protrusions116 can be of a consistent height, size or shape, or of a varied height,size or shape. The protrusions 116 can be tapered, such that protrusions116 closer to the first edge 102 are taller or shorter than protrusionsthat are closer to the second edge 104.

Referring now to FIG. 2, single face media 200 is shown, which includesa fluted sheet 210 and a facing sheet 220. In an embodiment, the facingsheet 220 can be substantially planar. In an embodiment, the facingsheet 220 can include a first surface 222 and a second surface 224.Facing sheet 220 contacts a plurality of protrusions 216 in fluted sheet110, which reduce masking between the fluted sheet 210 and secondsurface 224 of the facing sheet 220 by limiting contact between thefluted and facing sheets 210, 220.

FIG. 3 shows media 300 including a fluted sheet 310 and a facing sheet320. The fluted sheet 310 can included one or more protrusions, such asprotrusions 317 and 318. Protrusions 317 are disposed on one side of apeak 312 and a protrusion 318 is disposed on the opposite side of thepeak 312. In an embodiment, the peaks 312 do not contact the facingsheet 320, such as to prevent masking. The fluted sheet 310 can includeone or more ridges 326, as shown in FIG. 3. The ridges 326 can bediscontinuities in the curve of the fluted sheet 310. In an embodiment,the ridges 326 can be an inflection point, such as where the flutedsheet 310 changes from concave up to concave down, or from concave downto concave up. In an embodiment, the first protrusion 317 can bedisposed between a ridge 326 and a flute peak 312. The second protrusion318 can be disposed on the opposite side of the peak 312 and between thepeak 312 and a different ridge 326. The fluted sheet 310 can alsoinclude one or more additional protrusions 316, such as at peak 314 onalternative peaks as shown in FIG. 3. It will be understood that in someimplementations the protrusions 316, 317, 318 do not make contact with afacing sheet except when the element is under pressure, at which pointmedia deflection causes contact.

FIG. 4 shows a front view of a media pack 400 depicting a plurality offluted sheets 410 and a plurality of facing sheets 420. The flutedsheets 410 and facing sheets 420 are shown stacked on each other in analternating pattern. Fluted sheet 410 includes flutes 406 and 408.Flutes 406 are shown as having a significantly larger cross sectionalarea than those of flutes 408 in the depicted embodiment. This greatercross sectional area allows for a greater volume on one side of themedia pack. In some embodiments the side with greatest volume is theupstream side, which allows for greater dust loading volume on theupstream side of the media. In the depicted embodiment, peaks 412 do notcontact the facing sheet 420. The adjacent peaks 414 also do not contactthe facing sheet 420 in this depicted embodiment. The protrusions 416,417, and 418 are the only portions of the fluted sheet 410 thatsignificantly contacts the facing sheet 420 in certain embodiments.

This difference in upstream and downstream volumes can be characterizedas flute channel volume asymmetry (also called media volume asymmetry).Media volume asymmetry occurs when one side of a media pack (either theupstream or downstream side) has a different volume than the other sideof the media pack. Such asymmetry may be created by the manner in whichthe flutes are constructed, such as by having the flutes taper in crosssectional area. Media volume asymmetry, as used herein, generallymeasures the media volume ratio of the larger media volume bounded bythe flute peaks to the smaller media volume bounded by opposite flutepeaks. In some, but not all implementations, the larger media volumecorresponds to the upstream open media volume, and the smaller mediavolume corresponds to the downstream open media volume (during use theupstream volume may accumulate contaminants, such as dust).

Media volume asymmetry is beneficial for various reasons, includingimproved fluid flow and improved loading performance. In someimplementations media will demonstrate a media volume asymmetry of morethan 1%, more than 3%, more than 5%, or more than 10%. Example mediaconstructions demonstrate a media volume asymmetry of greater than 15%,greater than 20%, greater than 50%, greater than 75%, greater than 100%,greater than 150%, and greater than 200%. Suitable media volumeasymmetry ranges includes, for example, 1% to 300%, 5% to 200%; 50% to200%; 100% to 200%; and 100% to 150%. Tapered flutes may incorporatemedia volume asymmetry to further enhance filter performance.

Media packs containing tapered flutes may also demonstrate mediacross-sectional area asymmetry, which is calculated based upon across-section of the media at any given point. In a tapered flute, thecross-sectional area asymmetry will vary with measurement location alongthe depth of the fluted media pack. It will be understood thatcross-sectional area asymmetry may lead to media volume asymmetry, butthis is not always the case because tapered media cross sectional areascan be varied along the length of the flute so as to have a cumulativeeffect that the total volume on each side of the media is equal. Also, agiven cross section of a media pack may indicate a highercross-sectional area on an upstream side of the media, but subsequenttapering of the media could cause the overall media volume asymmetry tofavor the downstream side in terms of total media volume.

In some embodiments the media pack will have a cross-sectional areaasymmetry such that one side of the media has cross sectional area atleast 1 percent greater than the opposite side the same piece of media.Often the difference in cross-sectional area across the media will bemore than 3%, more than 5%, or more than 10%. Example mediaconstructions demonstrate a media cross sectional area asymmetry ofgreater than 15%, greater than 20%, greater than 50%, greater than 75%,greater than 100%, greater than 150%, and greater than 200%. Suitablemedia cross sectional area asymmetry ranges includes, for example, 1% to300%, 5% to 200%; 50% to 200%; 100% to 200%; and 100% to 150%.

The differences in cross sectional area are controlled by geometry ofthe flute design. Often the presence, number, and shape of ridges alongthe flutes significantly impacts the amount of cross sectional areaasymmetry. Tapering of the flutes will generally result in a change inthe cross sectional area asymmetry along the flute length. However, thisis not always true, such as when the height of a flute changes but thewidth is kept constant, such that the cross sectional area does notchange. In such embodiments it is sometimes possible to keep the totalcross sectional area constant by changing the relative position ofridges along the flute (or otherwise changing the distribution of themedia along the flute or by changing the radius of the flute).

Flute geometry that results in differences in cross sectional area cansignificantly impact flow properties through the flutes. Changes inrelative cross sectional area of flutes typically results in changes inthe cross sectional area of the upstream and downstream portion of themedia pack in that area: If the upstream portion of the media packundergoes an increase in cross sectional area, then the downstreamportion of the media pack will also typically undergo a decrease incross sectional area. The present invention allows for customization ofmedia volume asymmetry and cross-sectional area asymmetry to improvefilter performance.

FIG. 5 shows media pack 500 including a fluted sheet 510 and a facingsheet 520. The fluted sheet 510 can included one or more protrusions,such as protrusions 516 and 517. Protrusions 516 are disposed on oneside of a flute and protrusions 517 are disposed on the opposite side ofthe flute. The media pack 500 of FIG. 5 also shows ridges 526 and 527along flutes 506.

FIG. 6 shows a front view of a media pack 600 with a plurality of flutedsheets 610 and a plurality of facing sheets 620. The fluted sheets 610and facing sheets 620 are shown stacked on each other in an alternatingpattern, with protrusions 616 and 617 contacting facing sheets 620.Flutes 606 and 608 are shown depicted in FIG. 6. The upstream ends ofeither flutes 606 or 608 are typically plugged (such as by a bead seal,although it will be appreciated in some implementations the ends of theflutes are not plugged, or additional plugging occurs at other locationsalong at least some of the flutes), while the downstream end of theother flutes 606 or 608 are typically plugged near the downstream end ofthe flute. Thus, for example, if the upstream ends of flutes 606 areplugged, then the downstream ends of flutes 606 are typically open,while the upstream ends of flutes 608 are open and the downstream endsof flutes 608 are closed. It will be understood that often the upstreamflutes (those with downstream plug) have a volume greater than thedownstream flutes.

Now in reference to FIG. 7, an enlarged front view of a sheet of flutedmedia 710 and facer media 720 constructed and arranged according to anembodiment of the invention is shown with dimensions of example flutes.The fluted sheet 710 can includes flutes 706. The fluted sheet 710includes first flutes 706 on one side of the fluted sheet 710 and secondflutes 708 on the opposite side of the fluted sheet 710. The flutes 706in the depicted embodiment have a width A measured from a first one peak716 to adjacent peak 716. In example embodiments width A is from 0.75 to0.125 inches, optionally from 0.5 to 0.25 inches, and optionally from0.45 to 0.3 inches.

The protrusions 717 in the depicted embodiment have a width B. Inexample embodiments width B is from 0.2 to 0.02 inches, optionally from0.15 to 0.05 inches, and optionally from 0.1 to 0.075 inches. Width Bcan also be expressed as a multiple of the thickness F of the mediaforming fluted sheet 710. In example embodiments the width B is from 20to 1 times the thickness F of the media forming fluted sheet 710. Incertain embodiments the fluted width B of the protrusions is from 10 to7 times the thickness F of media forming fluted sheet 710. In someimplementations the protrusions 717 have a width extending along most orall of the flute width, such as the distance A′ shown in FIG. 7.

The flutes 706 in the depicted embodiment have a height C. In exampleembodiments height C is from 0.5 to 0.05 inches, optionally from 0.25 to0.075 inches, and optionally from 0.15 to 0.1 inches.

The protrusions 717 in the depicted embodiment have a height D. Inexample embodiments height D is from 0.1 to 0.005 inches, optionallyfrom 0.05 to 0.01 inches, and optionally from 0.025 to 0.015 inches.Height D can also be expressed as a multiple of the thickness of themedia forming fluted sheet 710. In example embodiments the height D isfrom 10 to 0.5 times the thickness of the media forming fluted sheet710. In certain embodiments the height D of the protrusions is from 2 to1 times the thickness of media forming fluted sheet 710. Also shown inFIG. 7 is the combined thickness E of the protrusion 717 and facer sheet720. In certain embodiments this combined thickness E will be from 0.11to 0.015 inches, or from 0.06 to 0.02 inches, or from 0.035 to 0.025inches. The height of the protrusions 716 can be similar or differentfrom the protrusions 717, and thus can be, for example from 0.1 to 0.005inches, optionally from 0.05 to 0.01 inches, and optionally from 0.025to 0.015 inches.

FIG. 8 is an enlarged perspective view of a sheet of fluted media 810constructed and arranged according to an embodiment of the invention,showing dimensions of example protrusions 872 on the media, and alsoshowing a flute peak 812. The protrusions 817 are shown with examplelength G, height H, and width I. The height of the protrusion can referto the distance between the top of the protrusion and the flat portionof filtration media, represented by line. In an embodiment, the averageheight of protrusions can range from 0.005 inches to 0.05 inches.

In an embodiment, the average height of the protrusions on a firstsurface can be less than or equal to 0.01 inches. In an embodiment, theaverage height of the protrusions on a first surface can be less than orequal to 0.05 inches. In an embodiment, the average height of theprotrusions on a second surface can be 0.0275 inches. In an embodiment,the average upstream protrusion height can be at least 50% greater thanthe average downstream protrusion height. In an embodiment, theprotrusions can have an average height of 0.017. In an embodiment theprotrusions have an average height of 500 to 50 percentage of the mediathickness.

The protrusions size or protrusion width can vary, depending on theapplication. The protrusions can vary in width from 0.2 inches to 0.02inches. In and embodiment, the protrusions have an average width of20000 to 200 percentage of the media thickness. In an embodiment, theprotrusions can cover from 20% to 1% of the surface area of thefiltration media.

FIG. 9 is a perspective view of a sheet of fluted filter media,constructed and arranged according to an embodiment of the invention,showing variable spacing of protrusions on the fluted filter media. Thefluted sheet 900 can include a first edge 902 and a second edge 904. Thefluted sheet 900 can include one or more flutes 906, such as a channelor a peak and a valley. The flutes 906 can extend from the first edge902 to the second edge 904. The fluted sheet 900 can include firstflutes 906 on one side of the fluted sheet 900 and second flutes 908 onthe opposite side of the fluted sheet 900. The flutes 906, 908 can beasymmetric, such as when the first flutes 906 have a different shapethan the second flutes 908. Distances between protrusions 916 are shownas distance D1, D2, and D3. In the depicted embodiment distance D1 isless than distance D2, which is less than distance D3. Thus, in thisexample implementation the distance between protrusions 916 increasesfurther from first edge 902. In other implementations the distancebetween protrusions 916 can decrease further from first edge 902.

FIG. 10 is a front view of a sheet of fluted filter media and a sheet offacer media 920, constructed and arranged according to an embodiment ofthe invention shown in FIG. 9. The facing sheet 920 can be substantiallyplanar. Facing sheet 920 contacts a plurality of protrusions 916 influted sheet 900, which reduce masking between the fluted sheet 910 andsecond surface 924 of the facing sheet 920 by limiting contact betweenthe fluted and facing sheets 910, 920.

FIG. 11 is a perspective view of a sheet of fluted filter media,constructed and arranged according to an embodiment of the invention,showing variable spacing of protrusions on the fluted filter media. Thefluted sheet 1100 can include a first edge 1102 and a second edge 1104.The fluted sheet 1100 can include one or more flutes 1106, such as achannel or a peak and a valley. The flutes 1106 can extend from thefirst edge 1102 to the second edge 1104. The fluted sheet 1100 caninclude first flutes 1106 on one side of the fluted sheet 1100 andsecond flutes 1108 on the opposite side of the fluted sheet 1100. Theflutes 1106, 1108 can be asymmetric, such as when the first flutes 1106have a different shape than the second flutes 1108. Fluted sheet 1100 inFIG. 11 does not contain a ridge, as shown in other embodiments such asthe ridge 326 depicted in FIG. 3. Instead, the fluted sheet 110 containsa curved profile. Also, in the depicted embodiment the peaks of theflutes contain a single rows of protrusions 1116 and 1118 positioned atthe peak of each flute 1106 and 1108.

FIG. 12 is a front view of a sheet of fluted filter media and a sheet offacer media 1100, constructed and arranged according to an embodiment ofthe invention shown in FIG. 11. The facing sheet 1120 can besubstantially planar. In an embodiment, the facing sheet 1120 caninclude a first surface 1122 and a second surface 1124. Facing sheet1120 contacts a plurality of protrusions 1116 in fluted sheet 1100,which reduce masking between the fluted sheet 1110 and second surface1124 of the facing sheet 1120 by limiting contact between the fluted andfacing sheets 1110, 1120.

FIG. 13 is a perspective view of a sheet of fluted filter media,constructed and arranged according to an embodiment of the invention,showing single protrusions on the fluted media sheet 1300. The flutedsheet 1300 can include a first edge 1302 and a second edge 1304. Thefluted sheet 1300 can include one or more flutes 1306, such as a channelor a peak and a valley. The flutes 1306 can extend from the first edge1302 to the second edge 1304. The fluted sheet 1300 can include firstflutes 1306 on one side of the fluted sheet 1300 and second flutes 1308on the opposite side of the fluted sheet 1300. The flutes 1306, 1308 canbe asymmetric, such as when the first flutes 1306 have a different shapethan the second flutes 1308.

FIG. 14 is a front view of a sheet of fluted filter media 1310 and asheet of facer media 1320, constructed and arranged according to anembodiment of the invention shown in FIG. 13. The facing sheet 1320 canbe substantially planar. In an embodiment, the facing sheet 1320 caninclude a first surface 1322 and a second surface 1324. Facing sheet1320 contacts a plurality of protrusions 1316 in fluted sheet 1300,which reduce masking between the fluted sheet 1310 and second surface1324 of the facing sheet 1320 by limiting contact between the fluted andfacing sheets 1310, 1320.

FIG. 15 is a perspective view of a sheet of fluted filter media,constructed and arranged according to an embodiment of the invention.The fluted sheet 1500 can include a first edge 1502 and a second edge1504. The fluted sheet 1500 can include one or more flutes 1506, such asa channel or a peak and a valley. The flutes 1506 can extend from thefirst edge 1502 to the second edge 1504. The fluted sheet 1500 caninclude first flutes 1506 on one side of the fluted sheet 1500 andsecond flutes 1508 on the opposite side of the fluted sheet 1500. Theflutes 1506, 1508 can be asymmetric, such as when the first flutes 1506have a different shape than the second flutes 1508.

FIG. 16 is a front view of a sheet of fluted filter media and a sheet offacer media, constructed and arranged according to an embodiment of theinvention shown in FIG. 15. The facing sheet 1520 can be substantiallyplanar. In an embodiment, the facing sheet 1520 can include a firstsurface 1522 and a second surface 1524. Facing sheet 1520 contacts aplurality of protrusions 1516 in fluted sheet 1500, which reduce maskingbetween the fluted sheet 1510 and second surface 1524 of the facingsheet 1520 by limiting contact between the fluted and facing sheets1510, 1520.

FIG. 17 is a perspective view of a sheet of fluted filter media and asheet of facer media 1700, constructed and arranged according to anembodiment of the invention, including a fluted sheet 1710 and a facingsheet 1720. The facing sheet 1720 can be substantially planar. Facingsheet 1720 contains a plurality of protrusions 1719, while the flutedsheet 1710 in the example embodiment does not contain protrusions. Thus,in this embodiment the protrusions 1719, projecting downward toward thepeak of the fluted sheet 1710 reduces masking between the fluted sheet1710 and surface of the facing sheet 1720 by limiting contact betweenthe fluted and facing sheets 1710, 1720.

FIG. 18 is a perspective view of a filter element 1800 constructed andarranged according to an embodiment of the invention. Filter element1800 contains a plurality of sheets of filter media. The filter element1800 can include a filtration media pack. The filtration media pack caninclude the fluted media with protrusions as described herein. Thefilter element can include a housing, such as to provide support for thesingle face media or configure the filter element to be mounted. Inexample embodiments the filter element 1800 is from 2 to 20 inches deep,in other embodiments the filter element 1800 is from 2 to 16 inchesdeep, in yet other embodiments the filter element is from 2 to 12 inchesdeep. In some embodiments the filter element 1800 is from 6 to 20 inchesdeep, in other embodiments the filter element 1800 is from 6 to 16inches deep, in yet other embodiments the filter element 1800 is from 6to 12 inches deep. Suitable filter elements 1800 can be, for example,from 6 to 10 inches deep. The constructions of the present invention,with protrusions separating the fluted and facing sheets, isparticularly advantageous with relatively deeper filter elements.

In certain implementations, the protrusions in the filter mediadescribed herein can have a height at least equal to the thickness ofthe media. In other implementations the protrusions have a height of attwo times the thickness of the media; in other implementations theprotrusions have a height of at three times the thickness of the media;in other implementations the protrusions have a height of at four timesthe thickness of the media; in other implementations the protrusionshave a height of from two five times the thickness of the media; in yetother implementations the protrusions have a height of from two to tentimes the thickness of the media.

The protrusions can also be measured by their height relative to theflute height. The flute height is that distance from the facing sheet totop of the flute. In some implementations the protrusions are less than90 percent of the height of the flute, alternatively less than 75percent of the height of the flute, and alternatively less than 50percent of the height of the flute. In some implementations theprotrusions are at least 10 percent of the height of the flute,alternatively at least 20 percent of the height of the flute, andalternatively at least 30 percent of the height of the flute. In someimplementations the protrusions are from 10 to 90 percent of the heightof the flute; in other implementations the protrusions are from 20 to 75percent of the height of the flute, and in yet other implementations theprotrusions are from 25 to 50 percent of the height of the flute.

The protrusions can also be measured by their height relative to theflute width. The flute width is that distance between adjacent same sidepeaks of the fluted sheet. In some implementations the protrusions areless than 40 percent of the width of the flute, alternatively less than30 percent of the width of the flute, and alternatively less than 25percent of the width of the flute. In some implementations theprotrusions are at least 1 percent of the width of the flute,alternatively at least 5 percent of the width of the flute, andalternatively at least 10 percent of the width of the flute. In someimplementations the protrusions are from 1 to 40 percent of the width ofthe flute; in other implementations the protrusions are from 2 to 20percent of the width of the flute, and in yet other implementations theprotrusions are from 3 to 10 percent of the width of the flute.

The protrusions are positioned on the peak, or maximum height point, ofthe flutes in some implementations, while in other implementations theprotrusions are placed on one or both sides of the flute peak. In someimplementations the peak of the flute is sharp or has a small radius,while in other implementations the peak has a gradual curve or issubstantially flat.

The protrusions can be substantially uniform in height, or can vary.Individual protrusions can have a varied height along its length orwidth. In addition, the heights of the various protrusions can varyalong the length of a flute. The variation in protrusion heights canpromote creation of media with tapered flutes that vary in height alongtheir length. In some cases the protrusions will get larger when movingfrom the upstream side of a media pack to the downstream side. In otherimplementations the protrusions are symmetrically aligned on both sidesof axis of flute.

The fluted media containing the protrusion on the flutes can demonstratearea or volume asymmetry. In the context of z-media, In general, areaasymmetry refers to an asymmetry in flute cross-sectional area, and canbe exhibited by tapered flutes. For example, area asymmetry exists if afluted area at one location along the length of a flute is differentfrom the fluted area at another location along the length of the flute.Because tapered flutes exhibit a decrease in size from a first location(e.g., end) to a second location (e.g., end) of the media pack or anincrease in size from a first location (e.g., end) to a second location(e.g., end) of the media pack, there is an area asymmetry.

Volumetric asymmetry refers to a difference between a dirty side volumeand a clean side volume within the filter media pack. Flute volumeasymmetry refers to a volumetric difference within a filter element orfilter cartridge between the upstream volume and the downstream volume.The upstream volume refers to the volume of the media that receives theunfiltered fluid (e.g., air), and the downstream volume refers to thevolume of the media that receives the filtered fluid (e.g., air). Filterelements can additionally be characterized as having a dirty side and aclean side. In general, the dirty side of filtration media refers to thevolume of media that receives the unfiltered fluid. The clean siderefers to the volume of media that receives the filtered fluid that haspassed via filtering passage from the dirty side.

In certain embodiments the media has a dirty side or upstream volumethat is greater than the clean side or downstream volume. It has beenobserved that in the case of filtering air, particulates in the air aredeposited on the dirty side and, as a result, the capacity of thefiltration media can be determined by the volume of the dirty side. Byproviding volume asymmetry, it is possible to increase the volume of themedia available for receiving the dirty air and thereby increase thecapacity of the media pack.

Filtration media have a flute volume asymmetry can be referred to as amedia pack having an asymmetric volume arrangement. Desirably, mediaexhibiting volume asymmetry has volume asymmetry of greater than about10%, greater than about 20%, greater than 30%, and preferably greaterthan about 50%. Exemplary ranges for flute volume asymmetry includeabout 30% to about 250%, and about 50% to about 200%. In general, it maybe desirable for the upstream volume to be greater than the downstreamvolume when it is desirable to maximize the life of the media.Alternatively, there may be situations where it is desirable to minimizethe upstream volume relative to the downstream volume. For example, inthe case of a safety element, it may be desirable to provide a safetyelement having a relatively low upstream volume so that the media fillsand prevents flow relatively quickly as an indicator that failure hasoccurred in an upstream filter element.

Filter element or filter cartridge configurations utilizing z-filtermedia are sometimes referred to as “straight through flowconfigurations” or by variants thereof. In general, in this context whatis meant is that the serviceable filter elements generally have an inletflow end (or face) and an exit flow end (or face), with flow enteringand exiting the filter cartridge in generally the same straight throughdirection. The term “straight through flow configuration” disregards,for this definition, air flow that passes out of the media pack throughthe outermost wrap of facing media. In some instances, each of the inletflow end and outlet flow end can be generally flat or planar, with thetwo parallel to one another. However, variations from this, for examplenon-planar faces, are possible in some applications.

The term “z-filter media construction” and variants thereof as usedherein, without more, is meant to refer to any or all of: a single facermedia containing a fluted media sheet and a facing media sheet withappropriate closure to inhibit air flow from one flow face to anotherwithout filtering passage through the filter media; and/or, a singlefacer media that is coiled or stacked or otherwise constructed or formedinto a three dimensional network of flutes; and/or, a filterconstruction including a single facer media; and/or, a fluted mediaconstructed or formed (e.g., by folding or pleating) into a threedimensional network of flutes. In general, it is desirable to provide anappropriate flute closure arrangement to inhibit unfiltered air thatflows in one side (or face) of the media from flowing out the other side(or face) of the media as part of the filtered air stream leaving themedia. In many arrangements, the z-filter media construction isconfigured for the formation of a network of inlet and outlet flutes,inlet flutes being open at a region adjacent an inlet face and beingclosed at a region adjacent an outlet face; and, outlet flutes beingclosed adjacent an inlet face and being open adjacent an outlet face.

In general, the filter media is a relatively flexible material,typically a non-woven fibrous material (of cellulose fibers, syntheticfibers or both) often including a resin therein, sometimes treated withadditional materials. In some embodiments the media fibers are primarilycellulosic. The media generally can be conformed or configured into thevarious fluted, for example corrugated, patterns, without unacceptablemedia damage. Also, it can be readily coiled or otherwise configured foruse, again without unacceptable media damage. Also, typically, the mediacan contain a resin. During the corrugation process, the media can beheated to above the glass transition point of the resin. When the resinthen cools, it will help to maintain the fluted shapes.

The filtration media can be provided as a relatively flexible media,including a non-woven fibrous material containing cellulose fibers,synthetic fibers, glass fibers, ceramic fibers, or combinations thereof,often including a resin therein, and sometimes treated with additionalmaterials. An example filtration media can be characterized as acellulosic filtration media that can tolerate about up to twelve percent(12%) strain without tearing when wet and warm, but which will oftenrupture at lower percent strain when dry and cold (as low as 3% withsome media). In an embodiment, the filtration media comprises cellulose.In an embodiment, the fibers forming the filtration media can include atleast 25% cellulose, at least 50% cellulose, or at least 75% cellulose.The filtration media can be fluted to form fluted filtration mediawithout unacceptable media degradation. In addition, the filtrationmedia is desirably of a nature such that it will maintain itsconfiguration, during use. While some filtration media is available thatcan tolerate greater than about twelve percent (12%) strain, and suchmedia can be used according to the invention, such media is typicallymore expensive because of the need to incorporate relatively largeamounts of synthetic fibers.

In the dimpling process, an inelastic deformation is caused to themedia. This prevents the media from returning to its original shape.However, once the forming displacements are released, the protrusionswill sometimes tend to spring partially back, maintaining only a portionof the stretch and bending that has occurred. Also, the media cancontain a resin. During the dimpling process, the media can be heated tosoften the resin. When the resin cools it helps to maintain the embossedshapes.

In an embodiment, the filter media can have a modulus of elasticity ofgreater than 10,000 pounds per square inch. In an embodiment, thefiltration media can have a modulus of elasticity of less than 75,000pounds per square inch.

The filtration media can be provided with a fine fiber material on oneor both sides thereof, for example, in accord with U.S. Pat. Nos.6,955,775, 6,673,156, and 7,270,693, incorporated herein by reference intheir entirety. In general, fine fiber can be referred to as polymerfine fiber (microfiber and nanofiber) and can be provided on the mediato improve filtration performance.

The fine fiber can be added at various stages of the manufacturingprocess. For example, in some implementations the media will containfine fiber before the protrusions are formed, while in otherimplementations the fine fiber is added as a layer or layers to themedia. As a result of the presence of fine fiber on the media, it can bepossible to provide media having a reduced weight or thickness whileobtaining desired filtration properties. Accordingly, the presence offine fiber on the media can provide enhanced filtration properties,provide for the use of thinner media, or both. Exemplary materials thatcan be used to form the fine fibers include polyvinylidene chloride,polyvinyl alcohol polymers, polyurethane, and co-polymers comprisingvarious nylons such as nylon 6, nylon 4,6, nylon 6,6, nylon 6, 10, andco-polymers thereof, polyvinyl chloride, PVDC, polystyrene,polyacrylonitrile, PMMA, PVDF, polyamides, and mixtures thereof.

Referring now to FIGS. 19 to 32, the relationship of various media andelement properties is shown for various example embodiments of theinvention in schematic form. In these constructions the x-axis showsdistance from the downstream end of the flute. Thus the “0” pointrepresents the downstream end of the flute, and the “300” point near theupstream end of the flute. The upstream end of the flute is located atthe face of the media pack where fluids to be filtered enter theelement, while the downstream end of a flute is located at the face ofthe media pack where fluids to be filtered exit the element.

FIGS. 19 to 21 show data from a first example embodiment of theinvention. FIG. 19 is a graphical representation of channel area andprotrusion height ratios of a filter media constructed and arranged inaccordance with a first example embodiment of the invention. In thisexample embodiment the protrusion height ratio stays substantiallyconstant, while the channel area ratio, measuring the channel area fromthe upstream portion of the element to the downstream portion of theelement, varies along an approximately 300 mm distance. Thus, theupstream to downstream cross sectional channel area ratio is higher atone end than the other of the media pack. Specifically, the upstream todownstream cross sectional area ratio shows a distinct reduction nearthe end of the element (near where fluids exit the element). Thus, theelement shows channel area asymmetry along most of its length, with theupstream cross sectional area of the element being greater than thedownstream cross sectional area of adjacent flutes for most of thelength of the element, but this difference in cross sectional areadiminishing as flutes progress to the end of the element where fluidsexit the element.

FIG. 20 is a graphical representation of corrugated and flat sheetlengths of a filter media constructed and arranged in accordance withthis first example embodiment of the invention. FIG. 20 shows how the “DLength” of the media, which is the width of one flute of media (such asthe length shown in FIG. 7 with annotation “A”), stays substantiallyconstant, while the length of the media along that flute (taken along across section of the flute planar to the flute length, which isrepresented, for example, in FIG. 7 as the length of media along theflute corresponding to the flute width of “A”), which is the “S length”,shows modest fluctuations along the flute length. These modestfluctuations in S length are a result of changes in the media lengthalong the flute as the result of the presence or absence of theprotrusions along each flute.

FIG. 21 is a graphical representation of upstream and downstreamprotrusion heights of a filter media constructed and arranged inaccordance with a first example embodiment of the invention. FIG. 21shows how the upstream protrusion height is less than the downstreamprotrusion height in this example embodiment. Thus, the downstreamprotrusion heights are greater than the upstream protrusion heights incertain embodiments of the invention. The increased protrusion heightsfor the downstream protrusions is beneficial in avoiding masking,because the downstream protrusions are sometimes under increaseddeformation pressure as a result the pressure differential between theupstream and downstream portions of the media pack when under load. Inthe example embodiment the upstream and downstream protrusions, althoughdifferent in size compared to one another, are uniform along the lengthof the element.

FIGS. 22 to 24 show element properties for a second exampleconstruction, specifically one with a fanned media pack, such as from acylindrical media pack. FIG. 22 is a graphical representation of channelarea and protrusion height ratios of a filter media constructed andarranged in accordance with a second example embodiment of theinvention. As is evident from FIG. 22, the dimple height ratio stayssubstantially constant along the length of the element in FIG. 22, butthe upstream to downstream channel area increases along the length ofthe element. This increase is somewhat variable to reflect changes inarea caused by the protrusions and the fanning of the media pack. Itwill be understood that in some implementations the channel area ratiowill show these fluctuations, but the fluctuations will be smaller thanshown in FIG. 22.

FIG. 23 is a graphical representation of corrugated and flat sheetlengths of a filter media constructed and arranged in accordance withthe second example embodiment of the invention. It is evident from FIG.23 that the “D Length” of the media, which is the width of one flute ofmedia, is constant, while the while the length of the media along oneflute, measured in the flute cross section (taking perpendicular to thelengthwise dimension of the flute), which is the “S length”, showsmodest fluctuations along the flute length, representing changes fromthe protrusion height.

FIG. 24 is a graphical representation of upstream and downstreamprotrusion heights of a filter media constructed and arranged inaccordance with the second example embodiment of the invention. FIG. 24shows how the upstream protrusion height is less than the downstreamprotrusion height. Thus, the downstream protrusion heights are greaterthan the upstream protrusion heights in the depicted embodiment. In theexample embodiment the upstream and downstream protrusions, althoughdifferent in size compared to one another, are uniform along the lengthof the element.

FIGS. 25 and 26 show element properties for a third exampleconstruction, specifically one in which the protrusions are tapered ineight relative to one another. FIG. 25 is a graphical representation ofchannel area and protrusion height ratios of a filter media constructedand arranged in accordance with a third example embodiment of theinvention. FIG. 25 shows how the dimple height ratio decreases deeperinto the element, and thus the upstream dimples decrease in sizerelative to the downstream dimples along the length of the flutes(viewing from right to left in FIG. 25, which is from the entry face tothe exit face of the media pack). FIG. 26 is a graphical representationshowing how in this example embodiment the upstream protrusion heightdecreases along the flute, while the downstream protrusion heightincreases, measured from right to left in FIG. 26.

FIG. 27 is a graphical representation of channel area and protrusionheight ratios of a filter media constructed and arranged in accordancewith a fourth example embodiment of the invention in which the upstreamand downstream protrusions have varying heights. FIG. 28 is a graphicalrepresentation of corrugated and flat sheet lengths of a filter mediaconstructed and arranged in accordance with this fourth exampleembodiment of the invention. FIG. 29 is a graphical representation ofupstream and downstream protrusion heights of a filter media constructedand arranged in accordance with this fourth example embodiment of theinvention.

FIGS. 30 to 32 show element properties for a fifth example construction,specifically one with a media pack in which the protrusions have a “wavepattern” in which the dimples are largest at the upstream and downstreamends, and smallest in the middle, of the element. FIG. 30 is a graphicalrepresentation of channel area and protrusion height ratios of a filtermedia constructed and arranged in accordance with a fifth exampleembodiment of the invention, showing how dimple height ratio staysconstant in this configuration, while the upstream to downstream channelarea ratio diminishes closet to the downstream end of the element. Inother words, the area asymmetry diminishes closer to the downstream endof the element. FIG. 31 is a graphical representation of corrugated andflat sheet lengths of a filter media constructed and arranged inaccordance with the fifth example embodiment of the invention. FIG. 32is a graphical representation of upstream and downstream protrusionheights of a filter media constructed and arranged in accordance with afifth example embodiment of the invention.

It should be noted that, as used in this specification and the appendedclaims, the singular forms “a,” “an,” and “the” include plural referentsunless the content clearly dictates otherwise. Thus, for example,reference to a composition containing “a compound” includes a mixture oftwo or more compounds. It should also be noted that the term “or” isgenerally employed in its sense including “and/or” unless the contentclearly dictates otherwise.

It should also be noted that, as used in this specification and theappended claims, the phrase “configured” describes a system, apparatus,or other structure that is constructed or configured to perform aparticular task or adopt a particular configuration to. The phrase“configured” can be used interchangeably with other similar phrases suchas arranged and configured, constructed and arranged, constructed,manufactured and arranged, and the like.

The invention has been described with reference to various specific andpreferred embodiments and techniques. However, it should be understoodthat many variations and modifications may be made while remainingwithin the spirit and scope of the invention.

I claim:
 1. A filtration media pack comprising: (a) a plurality oflayers of single face media comprising a fluted sheet, a facing sheet,and a plurality of flutes extending between the fluted sheet and thefacing sheet; (b) a first portion of the plurality of flutes beingclosed to unfiltered air flowing into the first portion of the pluralityof flutes, and a second portion of the plurality of flutes being closedto unfiltered air flowing out of the second portion of the plurality offlutes, such that air passing into one of the first face or the secondface of the media pack and out the other of the first face or the secondface of the media pack passes through media to provide filtration of theair; wherein the fluted sheet comprises a plurality of protrusions, theprotrusions being non-uniformly distributed along the fluted sheet; andwherein the fluted sheet comprises a plurality of protrusions offsetfrom the peaks of the flutes.
 2. The filtration media pack of claim 1,wherein the protrusions have a height of from 0.4 to 24 times thethickness of the media forming the fluted sheet.
 3. The filtration mediapack of claim 1, wherein the protrusions have a height of at least 2times the thickness of the media forming the fluted sheet.
 4. Thefiltration media pack of claim 1, wherein the protrusions are from 10 to90 percent of the height of the flutes in the fluted sheet.
 5. Thefiltration media pack of claim 1, wherein the protrusions between thefirst face of the filtration media pack and the second face of thefiltration media pack are of equal height.
 6. The filtration media packof claim 1, the flutes containing peaks, wherein the peaks do notsubstantially contact the facing sheet.
 7. The filtration media pack ofclaim 1, wherein upstream and downstream portions demonstrate anasymmetric volume.
 8. A filtration media pack comprising: (a) aplurality of layers of single face media comprising a fluted sheet, afacing sheet, and a plurality of flutes extending between the flutedsheet and the facing sheet; (b) a first portion of the plurality offlutes being closed to unfiltered air flowing into the first portion ofthe plurality of flutes, and a second portion of the plurality of flutesbeing closed to unfiltered air flowing out of the second portion of theplurality of flutes, such that air passing into one of the first face orthe second face of the media pack and out the other of the first face orthe second face of the media pack passes through media to providefiltration of the air; wherein the fluted sheet comprises a plurality ofprotrusions, the protrusions making contact with the facing sheet;wherein the protrusions are substantially absent from the portions ofthe fluted sheet not in contact with the facing sheet; and wherein thefluted sheet comprises a plurality of protrusions offset from the peaksof the flutes.
 9. The filtration media pack of claim 8, wherein theprotrusion comprises an island.
 10. The filtration media pack of claim8, wherein the protrusions have a height of from 0.2 to 3 millimeters.11. The filtration media pack of claim 8, wherein the protrusions have aheight of from 0.4 to 24 times the thickness of the media forming thefluted sheet.
 12. The filtration media pack of claim 8, wherein theprotrusions are from 10 to 90 percent of the height of the flutes in thefluted sheet.
 13. The filtration media pack of claim 8, wherein theprotrusions are less than 30 percent of the height of the flutes in thefluted sheet.
 14. The filtration media pack of claim 8, wherein theprotrusions are at least 15 percent of the height of the flutes in thefluted sheet.
 15. The filtration media pack of claim 8, wherein therepeating pattern of flutes comprises at least one ridge extending alongat least a portion of the flute length between adjacent peaks.
 16. Thefiltration media pack of claim 8, wherein the protrusions between thefirst face of the filtration media pack and the second face of thefiltration media pack are of equal height.
 17. The filtration media packof claim 8, wherein the protrusions between the first face of thefiltration media pack and the second face of the filtration media packare tapered in height with respect to each other.
 18. The filtrationmedia pack of claim 8, the flutes containing peaks, wherein the peaks donot substantially contact the facing sheet.
 19. The filtration mediapack of claim 8, wherein upstream and downstream portions demonstrate anasymmetric volume.
 20. A filtration media pack comprising: (a) aplurality of layers of single face media comprising a fluted sheet, afacing sheet, and a plurality of flutes extending between the flutedsheet and the facing sheet; (b) a first portion of the plurality offlutes being closed to unfiltered air flowing into the first portion ofthe plurality of flutes, and a second portion of the plurality of flutesbeing closed to unfiltered air flowing out of the second portion of theplurality of flutes, such that air passing into one of the first face orthe second face of the media pack and out the other of the first face orthe second face of the media pack passes through media to providefiltration of the air; wherein the fluted sheet comprises a plurality ofprotrusions extending from a remainder of the fluted sheet, theprotrusions having a non-constant cross-section on the fluted sheet inall axes; and wherein the fluted sheet comprises a plurality ofprotrusions offset from the peaks of the flutes.